The present invention relates to a gear shifting device and, in particular, to a gear shifting device for an automatic transmission of a vehicle.
Conventional arts include a gear shifting device for an automatic transmission of a vehicle disclosed in "the weekly service report" published by Nissan Motor Company Ltd.("Introduction of R32 type of automobile" Vol. 622; R32-1 pages C39 to C41, 1989) FIG. 1 is a schematic perspective view showing an essential part of the above conventional gear shifting device. As shown in the figure, the gear shifting device generally consists of a locking member 103 and a solenoid 105 as an electro-magnetic actuator both of which are arranged at a lower section of a shifting lever 101.
The locking member 103 is positioned under a positioning pin 107 and supported to rotate between a locked position and an unlocked position. The locking member 103 is provided with a slit 103a which allows the positioning pin 107 of the shifting lever 101 to be lowered at the locked position of the locking member 103.
The locking member 103 is connected with a solenoid rod 105a of the solenoid 105, which is urged to its projecting direction ( a direction shown with a letter A ) by a not-shown compression spring. When the shifting lever 101 is shifted into a "Parking" position of the gear shifting device, the solenoid 105 is inactivated, so that the solenoid rod 105a is pushed out by an urging force of the compression spring. Consequently, rotating to a direction of arrow, the locking member 103 occupies the locked position as shown in the figure. Under such a condition, since the positioning pin 107 is not in alignment with the slit 103a, the positioning pin 107 can not move downwards. Therefore, even if a knob button 111 of a knob 109 is pressed, a compression rod 113 having the positioning pin 107 fixed cannot be sunk any more, so that it is impossible to shift the shifting lever 101 from the "Parking" position to other positions.
When depressing a not-shown brake pedal under the above locked condition, the solenoid 105 is activated thereby to pull the solenoid rod 105a. Then, the locking member 103 is rotated toward the unlocked position, so that the slit 103a is brought into a condition that it is in alignment with the positioning pin 107. This disengagement the locking member 103 from the locked condition permits the positioning pin 107 to sink, so that it becomes possible to shift the shifting lever 101 upon disengaging the positioning pin 107 from a Parking position groove 115a of a positioning plate 115.
In the above-mentioned gear shifting device, however, if the solenoid 105 cannot operate normally, the shifting lever 101 is kept being locked in the Parking position, so that there is the possibility that the automobile cannot start to travel any more. In order to avoid such a problem, the gear shifting device of FIG. 1 has a hand operated locking disengageable mechanism as shown in FIGS. 2A to 2D.
The hand operated locking disengageable mechanism includes a disengaging lever 121 and a disengaging knob 123. The disengaging lever 121 is formed to be a bell crank. A base part 121a of the lever 121 is rotatably supported by the shifting lever 101 while a leading end 121b of the lever 121 is opposed to an abutting wall 103b of the locking member 103. On the other hand, the lever 121 is urged to a non-disengaging direction, i.e., a direction of B by a torsion coil spring 125. The disengaging knob 123 has a lower end connected with the disengaging lever 121 and an upper end extending into a vehicle cabin with the shifting ever 101.
In the case where the shifting lever 101 is shifted into the Parking position, if the electric system of the solenoid 105 fails, the locking member 103 would not rotate since the solenoid 105 cannot be activated in spite of pressing the brake pedal, so that it becomes impossible to operate the shifting lever 101 from the Parking position to the other positions. In this case, when depressing the disengaging knob 123 in the locked condition of FIG. 2A, the disengaging lever 121 is rotated as shown in FIG. 2B in a direction of an arrow C therein, opposing an urging force of the torsion coil spring 125. Consequently, the leading end 121b of the lever 121 presses the abutting wall 103b of the locking member 103 and then forcingly rotates it to the locking disengaging position, whereby it becomes possible to shift the shifting lever 101 from the Parking position to the other positions.
In the above-mentioned gear shift device, however, the handling of the disengaging knob 123 of the hand operated locking disengageable mechanism requires no special tool whereby the shifting operation of the shifting lever 101 from the Parking position to the other positions may be carried out against the driver's will. Therefore, it is desired to improve such a device.